As an example of a control unit of the hydraulic brake apparatus that automatically applies a hydraulic pressure to the wheel cylinder, a control unit having a housing in which bores for housing control valves, communicating passages for the control valves and the like are integrally formed, for example a control unit disclosed in JPH11-208440A, has been known.
In view of space efficiency in the control unit and connection efficiency of a conduit connected to the outside of the housing, such control unit has a structure in which a master cylinder port and a wheel cylinder port are arranged at an upper portion of the housing, a reservoir is arranged at a lower portion of the housing, and a pump, control valves, and outlet valves and the like are arranged at an intermediate portion of the housing. The outlet valve indicates a check valve used for preventing the brake fluid sucked by the pump from the reservoir from being flowing in an opposite direction. Within the housing, plural communicating passages forming a brake fluid circuit indicated in JPH11-28440A (illustrated in FIG. 4) are formed.
There is a need for downsizing and reducing a weight of the control unit of the hydraulic brake for the vehicle, however, as disclosed in JPH11-28440A (illustrated in FIG. 1), because the control valves are arranged above the pump in a two layered formation, a height of the housing may be reduced to some limited extents.
In order to achieve the space efficiency, in a case where a rotary pump is used, the control valves may be arranged so as to be along an outer circumferential surface of the rotary pump. In this configuration, however, the communicating passages for connecting the control valves may be interfere with each other so that the structure of the brake circuit may become complex. Such interferences of the communicating passages may be avoidable by providing a large sized housing, which is oppose the abovementioned need for downsizing the control unit. Thus, the interferences of the communicating passages have been an obstacle for achieving the downsizing of the control unit of the hydraulic brake for the vehicle.
A need thus exists for a control unit of a hydraulic brake for a vehicle, which is not susceptible to the drawback mentioned above.